1. Field of the Invention
The present invention relates to a multi-layer array type LED, and particularly relates to a high-strength airtight multi-layer array type LED capable of completely preventing moisture from permeating through to it, and being durable in use and capable of keeping the performance of optical devices for a long term.
2. The Prior Arts
The light-emitting theory of LED takes advantage of the intrinsic properties of semiconductors, which is different from the theory of electric discharging, heat and light-emitting of an incandescent light tube. Because light is emitted when electric current forward flowed across the PN junction of a semiconductor, LED is also called cold light. LED has features of durability, long service life, light-weight, low power consumption, and being free of toxic mercury, and thereby it can be widely used in the industry of luminance equipment, and LEDs are often arranged in an array and often used in such as electric bulletin board or traffic sign.
Referring to Taiwan Utility Patent No. M387375, which disclosed a multi-layer array type LED packaging structure, mainly includes a metal substrate, a package module, a lead frame, and a package cover. The metal substrate is positioned at the bottom of the packaging structure, and the package module is used for integrating the metal substrate with the lead frame. The LED dices are arranged in an array form on the metal substrate. The LED dices are electrically connected to the lead frame. The package cover covers the package module.
However, the conventional LED cannot be used in moisture and high humidity environments, such as deep sea, air space, or military. This is because each layer of the packaging structure is not completely air-tightly connected to each other, the airtightness is thereof gradually deteriorated, the moisture in the interior is increased, and each component of the packaging structure may be separated from each other, or may even be burned down and damaged. As a result, the conventional packaging structure can not be used in a moist environment, and the structural strength may also be gradually weakened. Therefore, the LEDs that have just been installed will need to be replaced after a short period of time. Maintenance and installation operations have to be performed every now and then in severe environment, and thereby time and labor are wasted and personnel safety is threatened. In view of the above-mentioned disadvantages, a LED packaging structure, which is capable of completely preventing moisture from permeating through it, being durable in use and keeping the performance of optical devices for a long term, shall be provided.